Objective 1- Create a distraction.

Ignore this message for a bit. first theres 2 guys at the beginning you need to shoot. Now go around and DON'T SHOOT anyone unless they see you and start firing. You will even hear something like "I got a visual on target!" IGNORE THAT KEEP MOVING. OK go into the alley on the left and turn right and you will see stairs. Go up the stairs and take out the guy on the fixed gun. Now activate the fixed gun and take out any enemies you see. you have men that help you with this, so go take out the tanker with the fixed gun. Wait, don't leave yet. After this, there will be briefings and things and then a car will be driving down the road in the distance. Stop the car by shooting the guy on the cars turret with the fixed gun. Now what I like to do here is get off the gun and take out my sniper. Zoom all the way and take out any guys you see that run up.

New Objective- Regroup at Parking Garage.

OK when they're all dead go back downstairs and head past the car. Take out your original weapon (machine gun). Be alert of your surroundings, because enemies can come out of no where. Turn left and use your scope to take out the enemies at the end of the road. Go to the end and head into the alley there. Use the restore point if you need to. Keep going but look out because there is a guy on the balcony around the corner. Take him out and keep going, and you will end up in the area where most people get stuck. I did. Take out the three guys with RPG's on the rooftops to the left.

New Objective- Demo building to create roadblock.

Run up to the part of the building where the objective marker is located, and there will be an option to place a bomb. Hit L1 to place the bomb, then run like hell to across the area! Boom. Okay so that takes care of the tank that was going to show up. Then 2 snipers will show up across the area on each side. Take them out. Okay so now Black Hawk 9 shows up, and gets taken down by RPG's.

New Objective- Cover President.

OK here is where I was stuck. I figured it out, though. Run over across from where you planted the bomb to demo the building. Turn to the building on your side, and there will be a ladder that is very hard to see, but trust me its along the building right across from where you planted the bomb. So if you find the ladder, climb it and at the top turn right and go around to run along the balcony. The first guy is hard to get because he hides under where you are, but the guys escorting the president will take him out. So now by about this time you should hear some beeping noise. At the top left of the screen is where that is coming from. hit the right D-Pad button so that you see what looks like a big red shield instead of your map. Then hit the UP D-Pad button to make the Guys escorting the president move forward. Take out any enemies ahead. The game guides you along the balconies a bit (there is only one way to go). When you reach the end of the balconies there will be a gate next to you. Just wait for a minute. Take out any enemies you see, there will also be some on the rooftop across from you. Then there will be an explosion that shakes the camera and vibrates the controller. OH HEY the gate opened! OK go through and go downstairs and out the door. Turn right (go around the car and half the road will be blocked off, just keep going to the right) and there are all your men waiting with the ATP and just like that you completed the mission!
Hope this answers all your questions about this mission.