No crank no start?

I took my truck to a mechanic shop last Wednesday due to knocking, and my truck would not turn over. I got it back that same Friday after the mechanic replaced the water pump, eight spark plugs, knock sensor and added coolant. I drove it that weekend along with Monday, Tuesday and Wednesday morning of the following week. Wednesday morning, I stopped at the gas station before work to grab some food and turn my engine off. When I came back out to leave my truck wouldn’t turn over, all It would do was click. My truck’s dashboard had a message that read, “battery weak, start vehicle” but again, would not start or turn over just clicked. My truck’s lights work, everything works but it just won’t start. I ended up taking the battery out myself and bought a brand new $200.00 battery. I put the brand-new battery in the same exact way I took the old one out but still won’t start just clicks. I’ve already spent $1,000.00 on my truck for these issues and have seemed to have gotten nowhere. Any chance someone could help me by posting a diagram of under the hood or of the starter and how to replace the starter. I want to save myself money and do it myself as I have a little baby due late next month.