Plugin Uploaded to Plugins Folder but Doesn’t Appear

Hi-

Can someone please tell me what I’m doing wrong? I’ve uploaded about five different plugins to the wp-content/plugins folder and none of them show up in the wp-admin menu under plugins, I only see the ones that were already there. Why don’t these new plugins appear? Is there something I need to refresh? I can’t activate the plugins I need because there is no where to activate them because their not in the list or on the plugin editor page. Please help me. Thanks.