2002 ford focus brake line.

That would be the Brake Service Light switch and it needs to be replaced.

Bleed ALL lines at calipers....

if it leaking brake fluid there, it would be your throw-out bearing! would also be the perfect time to replace the clutch! also, brake fluid will eat away the clutch disc lining!

check your brake fluid. If there is air in the lines this will cause the issue you are describing. Air in the lines is caused by a low brake fluid due to a leak in the brake line some where. If there has been a master brake cylinder repair some time since you owned it, then they did not bleed the brakes correctlyand get them to fix it. I am almost positive that if you check your fluid level and find it down, then you will have to bleed all your breaks. This is a tedious job and will need a couple of small containers of fluid to replace what you spill bleeding. If this doesn't fix it then you will need to replace the check valve, which controls the flow of the fluid from the front and rear brakes.

Add Brake Fluid and Bleed the Brake to get the Air out of the line. You will have to Bleed all 4.

There is air in the line try rebleeding the system if it was at a shop take it back soon

Remove wheel, brake drum, and brake shoes. The cylinder is the part the brake line goes into and it spreads the brake shoes apart when you brake.

Loosen the brake line but do not take off, unbolt the cylinder and then disconnect brake line. loosely connect the brake line to the new cylinder so you do not loose much brake fluid, bolt new cylinder in and then tighten the brake line.
Reinstall shoes. There should be a bleeding screw/grease head in the brake cylinder, loosen this and have someone step on the brake to bleed the line, have them hold the brake while you tighten the bleed screw. Do this as many times as necessary until brake fluid only with no air comes out.
Reinstall drum and tire, top off brake fluid.

There is no improper way to do it. Plan on fluid coming out of that hose and the line it is connected to. Remove the old hose. Install the new hose.
IMPORTANT: Bleed the line by having someone press and hold the brake peddle while you open the bleed screw at the wheel. (You could connect a small piece of plastic fish tank air line to the bleed screw to catch the fluid and allow you to conduct it to a bottle or jar.)
After a few seconds, retighten the bleed screw and have your helper pump and hold down the brake peddle again. Then you open the bleed screw again.

Repeat until no air comes out (fluid only).

Next, add DOT 3 brake fluid to the master cylinder.
Test for leaks.

do your brakes feel spongy? like too soft? . .n if it feels uneven maybe u may need to bleed your brake lines if u have to step too hard to brake . . u might be compressing air on brake lines intead of the fluid

Normal maintenance schedule at 75,000 miles:
Replace transmission fluid.
replace engine oil.
Rotate tires.
replace engine oil filter.
inspect brakes.
check parking brake adjustment.
inspect tie rod ends, steering gearbox and boots.
inspect suspension components.
inspect driveshaft boots.
inspect brake hoses and lines.
check all fluid levels.
inspect cooling system hoses.
inspect exhaust system.
inspect fuel lines and connections.

(At 90,000 do all of above plus:
replace air cleaner element.
inspect and adjust drive belts.
replace cabin air filter.)