you could do a few things.
1. Download the Autopricer in the Program Manager and use it to price the items for you. It will save time, but there is a problem that it may price the item very low if it detects another shop selling it at a ridiculously low price.
2. Manually check the shop wizard and price the items yourself. There's more control in this, but it will take up some time, especially if you have alot of items to price.
3. Check item databases for the pricing info (especially for Unbuyables (above 100k)) and put it up at the Trading Post for sale. Note that some of the prices for the items may be outdated and you may need to adjust how much of a profit you're willing to accept for the items, especially the HTS (hard to sell) items. Thing that are ETS (easy to sell) like the bag of peanuts, can be priced equal to the amounts indicated in databases and will still sell off quickly. Some HTS items you should expect to sell at 50% if you're lucky, or are interested in making a quick profit.
Hope this helps.