If your databases are in full recovery mode you will need to backup the transaction logs, when that is done you can shrink the log files and setup a regular log backup to minimize growth and keep good backups. I would reccomend that you read this: https://technet.microsoft.com/en-us/magazine/2009.07.sqlbackup.aspx but first things first.
The first step is to find the largest log files which you can shrink without backups - So you have to find databases which are in simple recovery mode:
select d.name, d.recovery_model_desc as recovery,d.log_reuse_wait_desc as wait_desc
,f.name as [LogicalName]
,CAST((f.size/128.0) AS DECIMAL(15,2)) AS [Total Size in MB]
from sys.databases d
inner join sys.master_files f on d.database_id = f.database_id
where f.type = 1
order by [Total Size in MB] desc
This will give you an output similar to this:
name recovery wait_desc LogicalName Total Size in MB
dba FULL NOTHING dba_log 4693.50
dbb SIMPLE NOTHING dbb_Log 1024.00
For each file which is in SIMPLE recovery and not having wait_desc = "active transaction" you can simply do
use database [NAMEFromQuery];
DBCC SHRINKFILE (N'LogicalNameFromQuery' , Truncateonly);
And then figure out why the log is growing.
Now for the databases in FULL Recovery mode you can do
ALTER DATABASE [NAMEFromQuery] SET RECOVERY SIMPLE WITH NO_WAIT
and then truncate the log as above to get out of trouble but remember which databases were in full recovery model.
Now read the article linked above and start making good backups.