In order to overcome fear brought about by Satan you must have a bold confrontation with him. Jesus confronted wicked spirits, and he was asking him, "What is your name?" And he said to him, "My name is Legion, for we are many." You must realise the fact that Satan is real, but a defeated foe (Col. 2:15) and greater is he that is in you than he that is in the world (1 Jn. 4:4). You must read and know what the Bible teaches about Satan and his evil devices and also about the authority of the believer over Satan.