How many Push ups should i do a night and how many cycles?

[Z Z]

Ok im a guy, im 16 and currently i can only do knee push ups.

At the moment i have been doing 10 at night around 3 times, i havn't timed how long i did them in between.

I want to get stronger so how many cycles should i be doing a night? have you got any advice? how many days should i do this a week?

Thanks in advance