New Newts - need help!

Hallo!
Yesterday, my dad finally gave in, and took me to buy 2 newts, which i was most pleased about. I also got a Resun Mini Filter, some gravel, the tank etc etc, and a hiding place.
But it seems they dont want to come out! i panicked today and rode my bike for about a hour to a little town called Ramsbottom, and bought some pH water testers and ammonia testers and it seems my pH is fine, and there is about0.25mg/l of ammonia in the water.
I am slightly worried about them, they dont seem to like the water, and sit in the shelter, which is half in water, half out, and seem to be half in the water.
Can anyoone tell me if this filter is ok too? it doesnt seem to be picking up the wate from the bottom of the tank, and if its a bit rubbishy, could someone tell me a really good filter for them? the tank is about length 24 inches, width 8 icnes, hight 8 inches with about 3 inches deep of water, and about 4 incges high of gravel, with a sloping plastic hollw tree on.

Newly purchased Cynops orientalis often cause this sort of problem. The animals you find and buy at petshops are WC, and exported from China. Those who survive the journey, are usually stressed, starved, ill or with a shredded inmune system.
Many develop illnesses, specially bacteria infections during the first few weeks. Others are so stressed they go into terrestrial phase, which is probably what´s happening to your newts.
That means, they will be fully terrestrial for a certain length of time. You can see if they are in terrestrial phase by the look of the skin. If it´s "warty" and repels water, they are terrestrial.
4inches of gravel sounds like way too much. Keep in mind, that gravel traps dirt. In deep layers of gravel, oxygen levels are too low, and nasty bacteria develop, converting waste into dangerous compounds.
If you use gravel, you should keep it as a thin layer, 1inch at it´s most perhaps.
Filters are not necessary, but if you want to use one, bare in mind it won´t "clean" your water...it will trap dirt, and help maintain water quality(if used properly), but you still need a cleaning rutine.

If your newts get to water, you should fill the tank as much as you can. The more water the better for you and the newts. Live plants are also a major help with water conditions, plus this species seems to love deep vegetation.

The large pile of gravel is the island for the newts to go onto when they dont want to swim - should i not be doing this? Can you suggest any other ways of cheaply making ground for the newts to sit on? Also, can you explain the filters that make bacteria, and could i set one up while my newts are in the tank?

Well, first thing would be to stablish wether your newts are likely to go aquatic or if they are in full terrestrial mode.
If they are terrestrial you should probably set them in a terrestrial temporary tank. Although unlikely, they can drown when their skin is designed for terrestrial purposes.
If you decide to keep them in the current tank...you can put floating pieces of bark as land areas, bricks that rise just above the water surface, etc. Some people go for those plastic things designed for turtles that stick to the glass.

Sponge filters help by providing bacteria with lots of surface, and oxygen, creating an ideal place for them to grow. Canister filters work the same way, except bigger and external. For a filter to serve it´s purpose properly it needs to be always on. If the oxygen suply stops for long periods, the bacteria die off. also you need to keep it reasonably clean, so that waste doesn´t clog the water flow.
I personally don´t use filters because i only keep still water species like Cynops orientalis. They don´t like strong currents. So if you do use a filter with them, it should make a gentle current. However, the filter can easily be substituted by live plants. That´s what i do. Lots of plants, and regular parcial water changes, and your tank will be in perfect shape. Apart from the fact that this way you eliminate the current, there´s the bonus of not having your water being heated up by the filter, which usually makes a small difference, but during summer that difference can be worthwhile.

Tanks should ideally be cycled before the newts go in. This is not always possible, as in your case, so to be on the safe side, you should increase the water level(ammonia will build up slowlier in a bigger water mass), and make 20% water changes daily. Always remember to use aged or dechlorinated water. If you keep the filter, it will create it´s own colony of bacteria once the tank cycles. The bacteria will grow on every surface, so plants, decoration, and stuff will help too.