While we do not write essays for students on this site, I'd be happy to give you some ideas about how to start writing it yourself.
It's always good to have a strong opening, a thesis statement that briefly states what your paper will be about, and perhaps why it is important. You might open with something like, "Understanding the important differences between personal and professional relationships can help pave the way to success in both aspects of a person's life." Expand on this with a couple of follow-up sentences, since paragraphs should generally be at least three sentences.
You'll want to have several more paragraphs which make your main points on the subject, each starting with its own topic sentence, followed by sentences which support that statement. Let's say you wanted one of those points to be the importance of keeping your personal relationships separate from your professional ones: "It is not always easy to keep professional relationships entirely separate from your personal life, especially if you socialize with your co-workers, after-hours." Give some thoughts on how it can be accomplished, such as agreeing not to talk about work outside the office. You might also want a paragraph on the similarities between personal and professional relationships, such as good communication skills being important to both.
Once you have made your main points in each subsequent paragraph, your last paragraph should summarize these points. Try to have a strong closing sentence which has a similar message to that of your thesis statement, but worded differently: "Building good relationships, both personally and professionally, is important, but knowing the difference between the two is vital."
I hope this helps!