I noticed from your earlier config that you were experimenting with port security. It's not going to make a difference performance-wise, and I'm not sure how much concern you have about non-authorized devices making physical connections to your switc...
I'd start with defining the first 24 ports as access ports. From the "Switch1(config)#" prompt, type "interface range gi1/0/1-24" which should take you to the "Switch1(config-if)#" prompt, and then type "Switchport mode access".I see that port 3 has ...
Ok, that makes more sense - it's a model 2960S-24PS-L which is 10/100/1000 on every port.Make sure you are in exec mode (type the word "enable" when you are at the "Switchname>" prompt). If you don't have a password yet, you will get the "Switchname#...
Something is wrong because WS-C2960S-F24TS-L is a 10/100 switch. The port names, and the ability to set them to 1000 Mbps doesn't make sense. Can you connect to it via PuTTY again and post the output from "show version" and "show run" commands?