I need three different letter of recommendations

If you can write three different letter of recommendations explaining how i would be a good candidate for the masters program in computer science. I don’t know much about what details to be included in the LOR. If you can use your expertise and make it seem professional that would be great. Two letters can be from a supervisor at a software company I worked for and third letter can be from a colleague. I am attaching my resume so that you can refer to it. For my name,  just write Mr. X. Describe my skills, accomplishments and personality. And for the name of supervisors and colleague use Mr. A, B and C.