Vegetable gardening in Klamath falls.  You stated you are new to gardening.  But you did not mention how long you have lived in Klamath Falls.  If you dont know, we have a very short growing season here.  Last spring frost can be as late as June 8 or so.  It can frost as early as mid September.  And I have been told it has even snowed in July.  So, my advice to you is to purchase tomatoes, peppers, cukes and other seeds/plants that have the shortest days to maturity you can find.  If you choose seeds, you should plant them now indoors.  If you get plants, I recommend getting them from a local company versus a big box shop.  Big box shops purchase nationally, so the varieties they have may have a longer maturity time.  A couple of tomato varieties that are early, are Early Girl and Early Boy, new girl, siletz.  Peppers need heat, so plant them in full sun.  California wonder bell and Recovery (early bell) are a couple of peppers.  Cukes, lemon, or armenian seem to do well.  These are varieties the Master Gardeners in Klamath Falls plant.  FYI, we will have a limited plant sale in early June, it should be advertised shortly.

Planting outside should be around June 8 - 10.  Pay attention to lows in the weather forecast. If it shows a freeze after your plant, you may have to cover to protect them.  I attach below a paper on best practices on short season vegetable growing.  

Best of luck to you!!  

https://www.extension.uidaho.edu/publishing/pdf/PNW/PNW0497.pdf

Here is a variety trial OSU did.  But this is for western Oregon, where here in KF, we are in southern Oregon.  It may give you some ideas, however.  

https://catalog.extension.oregonstate.edu/em877710

In case you are interested, the Master Gardener plant sale website is up and you can order plants if you like.  The site is kcmga.net .