Read ORS 166. ORS 166.173 has a got ya...some local governments restrict loaded OC, 173 is the law that allows them to. There is a sticky...read it.
ORS 166.250(3) states an openly carried handgun in a holster on your hip is not to be considered concealed.
ORS 166.260 is the execptions to .250. ORS 166.360-380 concern "public buildings". Unlicensed OC is not allowed in "public buildings" be sure you understand the definition of a "public building"
Other than in restricted cities, you can legally OC, unlicensed, in any county/state/national park, forest, or on BLM land. In the restricted cities you can still OC, but the weapon cannot be loaded. (a la California carry)
If you happen to come up to WA to visit whileon this side of the nation, be sure you are doing some recreational activity (like hiking, fishing, camping etc) or going to or coming from such activity. As you are under 21 you will want to make use of RCW 9.41.060(8) RCW 9.41.300 lists restrictions. WA has no restricted cities, everywhere in the state is the same law. One Caution In WA, no loaded long guns in any vehicle, ever...(F&W reg)
Neither OR or WA restrict carry very much, there are no "off limit" times or places in the forest and parks because an OC is considered a self defence weapon.
Take the time to read ORS 166 (and RCW 9.41 if you plane to visit WA)