Age: 14
Body type: Ectomorph
Access to weights and equipment: No
Height: 5'7 - 5'8

Ugh I saw another thread but didnt wanna overlap or ask my question there because it would overlap.

Im REALLY skinny.
Im underweight by like 20+ pounds or something

I can hardly do 3 pushups
I can do over 60 sit ups

I need help
What specific foods do I eat that I can find easily
What workout should I do if i cant access a gym and have no weights.
Should I even work out? Some ppl said i shouldnt right now...
Ty..