There are several ways of importing an EOS account to Wombat. One would be launching any EOS-based dApp or game, like Chain Clash. Another way is to go to your Wallet, tap or click on EOS and initiate a transaction. 

In both cases, Wombat will automatically take you to the account creation screen. Choose to import an account instead and enter your private key.

If you already have an EOS account created via Wombat, you will need to log out and log back in with the same Gmail, Twitter, Facebook or Apple ID account you used for creating that account. Be advised that it is not possible to merge different Wombat accounts with different login credentials.