Well, "Introduce Yourself" is the section where new members are supposed do exactly (and only) that, though very commonly also post more substantial questions. The various other categories/sections are home to discussions within their respective areas.
Your stamps are very common, and interestingly given inflation, may actually have face values less
than the paper they're printed on (mostly but not entirely joking
). We approach valuation the same way as any rational actor might: by factoring and weighing such things as catalog (Scott, Michel, Stanley Gibbons, etc) value, condition, provenance, and historical sales transactions.