That's great! You can vote for witnesses for example on my page over here https://primersion.com/witnesses/tangera04

Simply choose a few witnesses you want to vote for (me for example ;) ) and click on the checkmark on the right side. Then you have to sign the transaction using either keychain or hivesigner.

You should choose witnesses that you "trust" or witnesses who are actively contributing to make hive greater or witnesses creating interesting projects that you like.