http://www.gnu.org/software/emacs/manual/html_node/emacs/Package-Menu.html
1. install
list pacakges
choose you package with i and x to execute it
2. uninstall
list packages
choose you package with d and x to execute it

C-s
Incremental search forward (isearch-forward).
C-r
Incremental search backward (isearch-backward).