Bleeding cut on arm help?

when playing football on an astro turf pitch i got a friction burn just below my elbow about 3 cm lengh wise and 1 cm width and a scab formed just now i caugh the scab on a desk and it cut half of it off it started to bleed and because i couldnt have half it hanging off due to the pain it caused when i brushed my arm agaisnt clothing ect i riped it of and its really bleeding what would be the best thing i can do now thanks