3700 HP desktop printer

I am having trouble setting up my all in one 3700 series HP printer to my wifi it doesn't ask for a wifi name and password it just goes strictly by the signal I think the problem is the place I have my wifi gate way the signal nay not be strong enough to run the printer but I like my gateway where it is and I'm unable to put UT by a window like it's suggested my TV tablet and phone work very good an c the wifi signal is listed as excellent I just can't print from my tablet and phone I don't have a mail computer I tried to find a Ethernet cord well the one side is right for my printer but the other end is a USB port instead of that I need the other end to go in my tmobile gateway which is shipped like a telephone connector not a USB. Port I have a ethernet cord but the one side won't go into my printer but fits into my gateway