TrueCrypt now lives on as the open-source VeraCrypt. There are a lot of enhancements and security patches to the original TrueCrypt. If you wish to encrypt system partitions or volumes then you should check it out...otherwise, it is probably not what you want. A Google search for VeraCrypt will get you to the site quickly.
You can create a container with VeraCrypt, add files to it, and they will be encrypted. You can also configure encrypted backups, but that requires a backup app.
In any case, not all encryption apps do the same thing; some encrypt only partitions or volumes, others are limited to files, some in-between, etc.
From your original post it appears to me that you are either looking to encrypt files in batches, single files only, or both.
When it comes to encryption software I find that the choice is even more personal than selecting an AV - as encryption software can be quite quirky in regards to the user interface, the steps taken to perform encryption, system compatibility, etc.
You've already been given really good advice/options - so now you have to choose a few and then try them out.
NOTE: If what you are really looking for is automatic encrypted back-up, then there are online/cloud options
as well as apps. There is Duplicati. Others can be found by Google search "Automatic encrypted
backup."