For the weight you simply multiply the density by the volume and then multiply by the gravitational constant. This assumes that everything inside the football is the same thing (i.e. all meat or something else).
If you want to measure the density of meat, then what you need to do is get some standard container with a known volume (in cubic metres) and then get some scales and weigh the meat (i.e. what is on the scales minus the weight of the container), and then take that measurement on the scales (the weight in kilograms) and then divide this by 9.8 and then take this answer and divide it by the volume (in cubic metres which will be really small for a small container).
Now you need to find the volume of your football.
You do this by calculating an integral. I looked at a picture on Google and if the football is mostly circular at every cross section (i.e. if you sliced the football vertically then the cross section of the surface would look roughly like a circle) then you can use calculus to get the volume.
What you do is to fit a parabola and then use a formula in calculus to get the volume and you use this to get the weight.
I'll wait for your response before I go further.