Here are some ideas:
"Do men who receive education demonstrate increased adherence to recommended schedules for testicular self-examination than men who do not receive education?" Your sample could be recruited from a physician practice by having the office give introductory letters to patients within your desired age range with information about the study and a return postcard to indicate interest in participating. You could survey them about their practice before and after attending an educational program. (quantitative, correlational)
"What is the experience of men who have been diagnosed with testicular cancer?" You could recruit participants from an inpatient oncology unit or an oncology physician practice, with open-question interviews to describe their experiences and feelings. (qualitative)
If you just want to know whether men who are diagnosed with testicular cancer have performed self-exams, you have to relate the two somehow, and be able to state the purpose of your study. Maybe something like: "Does testicular self-examination lead to earlier diagnosis and more successful treatment in men who have been diagnosed with testicular cancer?".This would be a tough study to carry out, as you would have to do extensive chart reviews and follow-up studies. But since you're not actually going to do the research, it could work. (quantitative, non-correlational)
The first step is to determine what the problem is that your study will address, then do a literature search to determine what's already been done. Then formulate your question based on gaps in the literature regarding your topic. All research requires sampling, the tricky part is figuring out how to recruit participants. Incentives are nice, but you must be careful to avoid coercion. Don't forget to mention informed consent in your proposal. It's always good if your study can demonstrate value to nursing practice, such as showing that education by nurses increases adherence to treatment, or that increased knowledge of an experience can help to develop plans of care.
Good luck with your project, I just finished a grad-level research course and we had to write a proposal, it was tough but an interesting project.