If you cannot recognize the name of a country on a stamp, you may need a Stamp Identifier.
With the exception of Great Britain, all postage stamps must have the name of the country of issuance on them. (As the first country to issue postage stamps, Great Britain may simply have a silhouette of the ruling monarch.) However, the country name will not necessarily appear in English, or even resemble the English name.
Stamp Identifiers provide lists of the various text that may appear on stamps and tell you what country that text signifies. They can be purchased from suppliers such as Stanley Gibbons or Amazon.
While identification by country may initially satisfy you, many collectors will want to know when their stamp was issued and how much it is worth. Catalogues exist to help in this way. In the UK the Stanley Gibbons Postage Stamp Catalogue is the standard used by most collectors. In six volumes it lists nearly all the postage stamps issued by every country of the world. It is expensive to purchase a complete set but the catalogues may be borrowed from many public libraries. (Sometimes the most recent edition is in reference, but normally older editions may be checked out.)
Most catalogues are arranged by country and within country by type of stamp (such as regular, airmail or postage due) and date of issue. Look at the first few pages of a catalogue for information on how to use it. At first it can be challenging to find a specific stamp among the hundreds or thousands of listings for a country. However, in time looking at the denomination of the stamp and how it is printed (one or multiple colours) will give you good clues as to the approximate time the stamp was issued. Many modern stamps have the date of issue printed on them in very small figures somewhere in the design!