If you have not already done so, please read ComboFix usage, Questions, Help? - Look here
If you're interested in learning about malware removal and how to use advanced specialized fix tools like ComboFix, GMER, etc, please read BC Malware Removal Training
The above link explains how to apply and what is required. If there are no slots available, you will have to keep checking back at a later time. We are swamped with such requests and there are not enough instructors able to provide teaching so that limits the number of trainees we can accept.
Due to the self-paced structure of training and limited number of instructors here at BC, it is impossible to say with any accuracy when slots will open. New slots are opened up as our existing trainees complete the lower levels of study and move up toward more advanced levels. This is to prevent our volunteer staff being overwhelmed by an influx of new trainees. There is no notification system in place for when slots open so you need to keeping checking back if BC Study Hall is the school you prefer to enroll in. The logistics and management of such a notification system and the fact we have a worldwide membership negate the potential effectiveness and fairness one would expect from it.