Johnson, who took over from Ian Sampson, oversaw Saturday's 3-2 defeat by Shrewsbury and takes charge again at Chesterfield on Tuesday.
Harrad told BBC Radio Northampton: "He's got that aura about him. He's set the standard and the clubs he's been at says it all.
"I'm looking up to him and looking forward to working for him."
Harrad joined the Cobblers in the January transfer window, but the manager who signed him was sacked last week.
"I'm disappointed with Ian Sampson going but that's football unfortunately," said Harrad.
"I've got to look to stay in the team and be in the gaffer's plans."
Source: BBC Sport
Source: BBC Sport