1) Create a free account here. We need more information, and that will allow you to keep the answers in this thread, so we can all follow the conversation.
2) Are you getting any error message when it fails to connect?
3) Is there an "autoconnect" button (different manufacturers call it by different names but it's WPS - Wifi Protected Setup) on your router? (Make and model of the router?) Android phones and tabs seem to handle WPS really easily. Push the button and the phone basically "magically" connects.
BTW, you can't connect to just any wifi signal you see out there, even if it's not password protected. For one thing, that allows the people whose signal it is to access your phone - and do all sorts of nasty things to it. (It's worse than a public hotspot - no one knows that it was their signal you connected to, no one knows if they messed your phone up or someone else connected to their signal and did it - and it's all private with no record.)
For another, it's HIGHLY illegal in most countries. (In the US, the internet provider can sue you [and will get a judgement] for every month of service since those people first got internet service [or since you moved close enough to connect to their signal], because it's considered theft of service from the provider. That could end up costing you tens of thousands [or more] to save a few bucks a month.)