MissPistol:
You really need to read ORS 166.170 and following. Start here:
http://www.oregonlaws.org/ors/166.170 and then just follow the left column on down through the law.
Pay particular attention to ORS 166.173 especially as you live in the Portland area. Also, remember to study ORS 166.173(2)(c) and (2)(d). If you have an OR CHL you do not have to worry about Portand and Multnoma Co's restrictions. If you do not have a CHL you do need to read Portland and Multnoma Co's ordinances also.
Next section to pay particular attention to is ORS 166.250 (prohibitions) and ORS 166.260 (Exemptions) Read carefully, and remember, that which is not prohibited, is permitted. In OR it is very useful to have a CHL (particularly in Portland) even though unlicensed OC is legal (ORS 166.250(3))
A very good summery of the law is at
www.handgunlaw.us