There is no standard number that your credit score will go up each month if you have a secured credit card or line of credit of any other kind.  There are a wide number of factors that determine your credit score and these factors are all based on your behavior and not on what type of or how many credit cards your have.  Plus your credit score is calculated based on your overall credit history, not just the activity on one account.
A secured credit card works just like any other credit card, expect for the deposit that’s required to open the account.  If you are opening a secured card account because you have no credit or bad credit, then you should see an improvement in your credit score, provided that you manage your secured account responsibly by paying your bill on time each month and being careful not to go over your credit limit.
Following these rules will lead to an improvement in your credit score.  However, if you mismanage a secured credit card account by going over the limit and/or not paying your bills on time, then your credit score will drop, just as it would if you did this with a traditional credit card.