Since you were not able to get a clean hefsek taharah, you will need to try again tomorrow afternoon. Here are a few tips that we hope will help you avoid difficulties in the future.
When you attempt to perform your hefsek taharah, you should leave yourself adequate time so that if your first attempt is not clean, you will be able to wait and let your body relubricate itself before making a second attempt. If you see that after a few attempts you are still finding blood on the cloth, you should wait until the next day to try again so as not to irritate yourself.
Remember that a hefsek taharah does not need to be absolutely clear. If a stain is not red or black you should bring it to a rabbi for evaluation since there are some shades of brown that are acceptable.
Use the softest cloth you can find – you could even cut up well laundered white cotton underwear – and slightly dampen the cloth. Go very gently. Some women are more comfortable with one leg slightly elevated on a stool. Others find it helpful to lie down.
It is important to remember that the vaginal canal is formed by muscles that can be contracted and relaxed. Anxiety causes one to tighten the muscles and thus narrows the opening. Relaxation helps keep it open. Therefore, techniques that increase relaxation (e.g. deep breathing, listening to music, thinking calming thoughts) can help make these bedikot easier as well.
If you encounter this type of problem with the bedikot of the seven clean days, you should also ask your rabbi about possibly reducing the number of bedikot you need to perform during the clean days.
B'Hatzlacha!