I am new to running....just made it to the three mile mark upright without walking!! My friend asked me to do a half marathon in February... Is it possible to walk/run that distance by that time? Is it unsafe to run/walk that distance so new to the sport?
First of all, congratulations on taking up running and I wish you lots of happy miles.
No problem with setting goals, as long as you train properly for them and do not overdo it. Running can sometimes be tough (specially at the begining), so you should focus on enjoying your runs at first.
Once you have achieved that, improved your fitness level a little and are more confident with your running skills, there are many training plans for HM out there, from walking to elite, a quick search led me to Hal Highdon's plans which might be useful for you.
You have some time for training, but the half is a real challenge, so I would recommend that you go through the ranks and complete some 5k, 8k and 10K races before February. Those will give you greater experience and perspective with building confidence and endurance. I would never suggest the half as your first race opportunity, because that environment is much different than personal training.
Specifically, it is certainly okay to run/walk for most events, but you still need the preparation base to handle the distance.
Wishing you all the best and get in those entry forms.