Hi Rebecca -
You and your brothers should consider contacting an experienced Oil and Gas Attorney. The Texas State Bar Association's website has a directory of attorneys from all over the state.
In addition to that, there are several experienced Landmen, including myself, that are members of The Forum. We have all been answering questions for Land and Mineral Owners for years and years and I am sure we will all be happy to help.
If an oil and gas company has contacted you about leasing your land, then you own at least some of your mineral rights. They send Landmen out to check the County Records about that sort of thing before they contact anybody.
Ask them to provide you with a copy of their Mineral Ownership Report (MOR). A report like that will list everybody who owns minerals in the subject land(s).
You can also ask them for a map of the property(ies) if you do not already have one.
No, you do not need to sign the lease right away. As a matter of fact, you shouldn't do anything right away. There are a number of issues you will need to learn about before making any kind of commitment. Don't let them rush you into anything. And don't worry, they won't be going away anytime soon.
How much acreage have you inherited and where is it? Do you have a legal description for it?
Hope this helps -
Charles Emery Tooke III
Certified Professional Landman
Fort Worth, Texas
PS: Calm down, slow down and don't forget to breathe. Nothing bad is going to happen. As a matter of fact, several really good things more than likely will.