If you want point in time recovery, you need to have log backups. Set them up, maybe once an hour to start, and keep all log backups since the most recent full. that way you can recover to a point in time.

A log backup will mark those transactions in the log as free, and the space can be reused. Note how big your log backups are, and then you can shrink the log to hold that much data, plus some pad. Likely your log is much bigger than it needs to be. However, a shrink should not be done regularly. Just for one-time events, like this, and use DBCC SHRINKFILE.

You can read about the backup command in books online to understand what the truncate does. Basically it's an emergency measure when you have filled the disk. If you haven't don't run it.