For most people, the usual:
./configure
make
sudo make install
is enough. This installs Dovecot under /usr/local.
If you have installed some libraries into locations which require special include or library paths, you can give them in CPPFLAGS and LDFLAGS environment variables. For example:
CPPFLAGS=-I/opt/openssl/include LDFLAGS=-L/opt/openssl/lib ./configure
See ./configure --help for a list of all available configure options.
See http://wiki2.dovecot.org/CompilingSource for more information.
Start with the example configuration:
cp -r /usr/local/share/doc/dovecot/example-config/* /usr/local/etc/dovecot/
Read through, and make needed modifications.
Once everything is configured, start Dovecot by running "dovecot" binary.
See Wiki for more information about configuration. If you're in a hurry, go at least through http://wiki2.dovecot.org/QuickConfiguration
Dovecot used to support both GNUTLS and OpenSSL libraries, but nowadays only the OpenSSL code is working.