I use metamask custom RPC and set it to be http://myip:8545, and it looks like keep trying connecting, but always not finish, actually I am using private ethereum network, whether I must mine on my private network to make the metamask ok?
Do you have Genache installed? If not, You have to have a local instance of the blockchain running on your computer in order to use the custom RPC.
If you do have Genache installed then copy the data called RPC server at the top of the genache client and use it as your custom RPC. Hope this helps.