Help with Connection?

Recently my internet signal has been going in and out. I used to have a linksys router which gave me horrible connection. I bought a Netgear route not too long ago which has been better but I'm still unable to get a solid connection. The router is connected to a desktop and is wirelessly connected to both my iMac and a separate hp laptop. The connection given with the Netgear router wasn't great but it never gave me any trouble. About 6 weeks ago it has been coming up with a weak signal or none at all. The Netgear router i have now is the WNDR3300 and i noticed a 5gHz feature, how do i use it. It is also dual band it had a G network and a N network. But i'm not able to connect to my N network. I reset my router to try and fix the problem and now i have a unsecured network with the default name and i don't know how to change it. I"m quite computer illiterate so if u can plz answer in as simple terms as possible.