2nd router help plz

first off sorry for starting another thread but the old one is closed

I have been trying to extend my network with a second wifi router i cant get it to work at all and im new to networking usually been able to make due with 1 4port router til recently. I need to get internet and wifi out to my garage for work the fastest and simplest way to run and set up devices is what im looking for. I dont know what info u will need so ill post everything i can as soon as i know what i need to give you.

Thanks in advance everyone