Check the minimap frequently to see where the beam is currently. It is enough time to complete all objectives. It will reach the technology vault after about 20 minutes of the game. After a while, the path of Tal'Darim laser will appear on the map. You will have a well developed base and a very small army. This Team Liquid forum post goes into great detail about the shortcomings of the current custom map system and the workarounds for it. You start in the southern part of the map. It is very difficult for a new map to make its way up through the popularity list with this system. Unfortunately, this will create a copy on their server, and anyone found playing your copy will be counted differently from the original author's copy, which means that the stats for determining popularity will treat them as separate maps even though they are the same.
Caution: Before using cheat codes, it’s important to understand that using them will prevent additional achievement gains you might have earned through normal play until either a new campaign is. You have to open the map in the map editor and publish it just as you would any of your own maps. Cheat codes can be used in single-player campaign mode by pressing the enter key during the game and typing the codes shown below in the console. Ideally, you can find it in the search engine online, but there are a limited number of maps that appear in that, so if the map you want to try is unpopular, your only option is to publish it yourself. Rather, to answer your question, the only way for you to play this map is to either find it in the search engine for custom games online or to publish it yourself. Many view this as a downfall in their current system, but this site is not the place for such arguments. Actually, the way Blizzard has custom games working at the moment, it is not as simple as navigating to a folder to select the map.