that can be a tough question
When you first start the wallet, it looks at a dnsseed address(es) that is hard coded in the wallet. that is where it gets more wallets to connect to.
the very first time you open your wallet - like after installing it - or if you removed the blockchain database, the wallet spends most of it's time downloading the missing blocks from the very first connection. is does add more as time goes by - you should have more connections within a few minutes.

I'm guessing that is not your issue.

In some instances, and I don't know why (maybe a firewall, or isp issue? ya, if you can connect to 1 - then why not the others...)
you may need to add some connections manually in a configuration file.

If you are running a linux flavor - you probably already know the file.
In windows, the conf file is not required for the wallet to run.
Here is an example to add to windows, if you haven't all ready. The file name is: BitcoinFast.conf
and it goes in this location: C:\Users\*yourname*\AppData\Roaming\BitcoinFast\
then start your wallet again.

you don't have to remember the rpc user or password.
You can get a current list of nodes to add at http://Bitcoinfast.co under the status tab

sometimes it is as easy as shutting down the wallet, say "work darn you" - and start the wallet again