Login with captcha. Protect your login page from Brute-force attacks also you can track login history. Features:

• Captcha on the admin login page to protect against auto-hacking.
• You can set the number of failed logins to show Captcha or showing it always.
• Login Blocker option to block the login processe for a period of time after specific number of failed logins.
• Login history to show all login processes in details.

• Go to the wordpress control panel and go to "Plugins" menu and press the button "Add New".
• Go to the tab "Upload" and choose the file "better-login-security-and-history.zip", click the button "Upload" to get the file uploaded.
• Lockup the plugin, and click "Activate" to get it active.
• Go to the Options page and configure the plugin.

view this posts if you want more details about installing plugins: http://www.wpfasthelp.com/how-to-install-wordpress-plugins.htm