You can search your Bitlinks several ways. The first is through the "Search" box at the top of your screen.
You can also "Filter" your Bitlinks by clicking on the filter button located in the top right corner below "Create Bitlink" or "Create" button.
From there you will have three options for how to filter your links. You can filter by Tags, Custom Bitlinks, or Hidden Bitlinks. Once you chose the filter, the "Apply" button will populate, and when you click on it the filter will run.