I will review the steps that need to be take to implement this, please respond to the step you are on currently and let us know what you have done and what the result is.
1) first make sure that the price for the option is stored in the db, the best would probably be to store it with the record for a particular option, like size large has an extra cost of $x.
2) once you are storing the price along with the option you will need to get your add to cart page setup. You should get this page working without the options affecting the price first.
3) when the add to cart page is working you will want to modify it. The first thing you will do is add a recordset to select the product options. Next you will add in a select list inside of the add to cart form. When you add this list you will populate it from the just created recordset.
4) you should now have a working add to cart page that has a select list for the options. You should ensure that the select list is using the records id as the value and the name of the option as the label.
5) with your options select list on the page you will add another recordset to the page, this new recordset will be like the last options recordset you have on the page but it will be filtered by the posted option id from the options select list.
6) finally, after you have your new filtered recordset in place you will have the options values available to the code on the page. You can get back any info about the option by referencing the newly filtered recordset on the page. You can add the price to the price of the item, or use the options price in place of the regular price, however you would like it to work.
Please review these steps and post back about the one you are at currently. Please post back and let us know what you have tried for that step and the result you are getting. You should not move to the next step until you finish all previous steps.