If you want to send offers to eligible buyers (assuming you have watchers or viewers who have not opted out of seller initiated offers) you can go to your Active Listings page and click on "Send Offers - Eligible" above the list of items. It'll filter the list so you can see which items are eligible to send offers, and also change the default choice to the left of each item to Send Offer. You can do offers one at a time or in bulk.
To offer sales or discounts, other than through offers, you go to the Seller Hub -> Marketing -> Discounts, and set up whatever sale you want, choosing by item or by category to decide which of your items qualify. You have a Store Subscription, so this should be available to you.
