From Desert Operations Wiki
There are other ways to obtain buildings fast, besides research and constructing them, and that's attacking other players. Winning a battle could benefit you with capturing a maximum of 33% of the enemy's buildings. To receive this 33%, you must destroy at least 80% of the enemy's total power defense value with your attacking force. Warning! Don't confuse the number of defense units with their defense values, and to get this last number, as a good General, you should multiply the defense value to the quantity of defense units of your enemy. That will help you to calculate appropriately your attack against this units. Sure, you could try a brute force attack and send everything but it may help to do some math once in a while.
After your first attack against your opponent, the percentage of maximum losses will diminish this way: 33%, 33%, 25%, 15% and 5% (Every server can have different values). After 12 hours (Also changes in different servers), the percentage will rise again to 33%. The system does not allowed to launch more than five attacks simultaneously against the same player. You may only attack a player that has a 67% less or 150% more than your points. You'll see that easily when you look their names in the ranking or in their sectors, if they're white, they can be attacked.
Remember that the Newbie protection is lifted after you gain more than 13.800 points or after you do your first attack. Attacks and the management of their units, can be done in Base > Command Center > Military.
Important! Whenever a new world or server is started, the rookie protection will be deactivated the first two weeks and everything goes. You can attack anyone and anyone can attack you.