I just finished a GD pregnancy. There are some good support groups on FB if you are on there at all. Just search gestational diabetes to find groups.
Here is what you will likely encounter - they'll tell you to limit and spread out your carbs through the day. Your recommendations may be different than mine but basically I was told to alternate meals and snacks, eating every 2-3 hours. Carbs, for me, were 30 - 15 - 45 - 30 - 45 - 30. That was breakfast, snack, lunch, snack, etc.
Walk, exercise some right after eating.
You'll be required to test your blood several times a day, possibly starting off with 6 times (before and after meals) then when they have the baseline set, you may drop down to 4 or fewer times a day. They'll say test fasting (when you first wake up) and then before eating and either 1 hour or 2 hours after eating. One hour tests how high the sugar spike goes. Two hours tests whether your body can come back to baseline with fewer problems.
If you can't stay within test limits, they SHOULD tweak diet and exercise first, then go for medicine - unless your numbers are just wildly crazy. If you do need medicine - you'll be offered either pills - gly-buride or metformin, or insulin. The insulin can be fast acting or slow acting. Some I knew had to do a little of both types of insulin.
Carbs are very fun to count. Many root veggies - carrots, potatoes, turnips, etc. are carbs. So are many squashes - pumpkin, butternut, acorn, etc. You'll want to match up a protein with a carb. Protein helps slow the absorption of the carb sugars.
Your dietician will provide you with handouts that detail all the carbs, what counts as sugars, what veggies are "free" and can be eaten at any time even if it is within your test period.