WebPart Help

Hello Guys, I know this is a wrong forum to place my problem but I am very
desprate to find a solution. If any one of you is workign with coding and
deploying Sharepoint web parts please help me with this. Any suggestions
welcomed.

I really need help with this. I am stuck on this validation process since last
week. 

Scenario.
OK. There is a Sharepoint List. It has list of all the rooms booked for current
date and forthcoming dates. This list comprises of information like: 
Event Title, Start Time, End Time, Location. 

Key Point #                Format of DateTime in Sharepoint List Items 'Start
Time' and 'End Time' is 14/09/2006 14:00

Now, I have made a Web Part with custom controls. I have a Calendar ( so users
can select a booking Date) and 4 dropdownlists for time selection. Something
like this.

Event Start 08 09 10 11 12 13 14 15 16 17 18 00 30Event End 08 09 10 11 12 13 14
15 16 17 18 00 30

Now, Problem -- Guys I need to validate if there is a booking existing then
display 'not available' However if a time slot is available then I would like to
add a booking to the SharepointList.

Don't worry about displaying messages just tell me how should I compare
Sharepoint List Items with the values taken from Calendar and these
Dropdownlists. Below is a picture ( of Sharepoint List) for you to understand
better. How do I compare Begin and End with my DropDownList selectedValues. 

TitleDepartmentBeginEndRoomTeam MeetingSales and Marketing07/06/2005
16:0023/07/2024 17:00Auditorium

 

HELP