Be aware that the Dallas Skywarn nets on 146.88 are all RACES nets and you'll need to provide your RACES number to join and participate on the net as an active member. Station locations are also reported using grid coordinates, not the typical addresses, cross streets, MAPSCO grids, or GPS coordinates. Previously they accepted most of these, but have changed the rules to provide better locations to the NWS. There was just too much confusion with things like "Was that North Marsh Lane, or South Marsh Lane" and since Mapsco changed up their grid system the confusion was "What year is your MAPSCO" or "are those new or old grid locations".
Much of what you'll need is on the Dallas County RACES web site (
Dallas RACES). You'll need to submit your application to your specific area's radio officer and have that approved (the list of radio officers are on the web site). There are also various requirements that a spotter must have prior to joining, such as have a valid ham license, a 2 meter radio capable of operation on the net(s), been to a recent NWS Skywarn training class (Basic required, Advanced preferred) and must have been within the most recent two years, completed some specific FEMA training classes, and several others (they're listed in the Requirements section of the linked to above web site).
Also be aware that although the Dallas County net is on 146.88, there are also nets for various cities within Dallas County. Depending on the city and/or incident there may be nets on the city(s), main county on 146.88 or both. Also note that some repeaters may use a PL tone during normal operation and may turn the PL tone requirement off during a Skywarn net (you can leave your radio set to transmit the tone, but will need it programmed for no tone on receive to hear the net). This is to eliminate PL related issues for folks sending reports on the important Skywarn nets. Your radio officer can provide details on specific repeaters and the training nets are generally a great way to confirm that your radio is correctly programmed for net operation prior to an emergency situation.
One other suggestion is to read through the most recent copy of the "Cloud Cowboy" reference manual, which is the general reference for emergency operation nets in the Dallas County area. A link to this is on that web site.