Big job for a DIYer. Depending on whats under the vehicle you could be removing all kinds of skid plates, steering components before you could gain access the oil pan. If your lucky enough to gain access, remove all bolts around it outsides then go down to your local parts house and get a good quality set of gaskets. Next give it a good cleaning making sure to check the bolt holes to see if they have been bent inward. When replacing the gaskets you may want to use something like a silicone to help keep the gaskets to stay in place but whatever you do only a small amount should be used. Reverse the process and your set to go. . . well somewhere!