When do I use these words?

English as a Second Language English Vocabulary, Grammar and Idioms
1

Hello

I don’t know when to use: would, could, should…
Can you help me please ?

2

I would do it if I was able.

I could do it.

I really should do it.

3

Thanks a lot Kitosdad

I’ll try to do some sentences. Can you correct them please?
Here are the sentences: I can learn to speak English fluently in one month
Can some body help me to solve this problem ?
I could prepare Cameroonian dishes if my mother taught me
I wil travel to Bombey
I would learn Chinese in six month if I had Chinese friends