You don't have to be an expert to do this. Call a hotel you're interested in and ask for the sales department. Tell them what you want in terms of date(s) and number of rooms. Also tell them you've never done this before, so they'll have to be patient with you and explain the process a bit more than they would with an expert.

The most important things you want to know are (a) how much they'll charge per room and (b) when they'll release rooms that your group members haven't reserved yet. You can compare your group rate with the rates the hotel offers online for seniors, auto club members, government employees and so on. If you're not getting much of a discount, you can use that as a basis for negotiating.

If your group might also need function rooms and order food, be sure to mention that.

It's OK to compare several hotels. After the second one, you won't need the "I've never done this before" line.