You can search your entries by using the global search bar in the main site header or by clicking "View All Entries" and searching / filtering there. Sometimes it can take up to a few hours for new entries to pop into the search database, so if you are searching for something you just wrote and it's not showing up, try again in a few hours and it should be there.
Any entries in an encryption locked journal are not searchable. Once an entry is encrypted, the contents aren’t visible by anyone unless they have the encryption key. This includes us, and so we can't search encrypted entries unless they are unlocked.