Help with coding command button in user form

[monsta7144]

Hello,

Firstly, this is my first time posting so i apologize if this is in the wrong place. I have a spreadsheet for fuel issues for equipment with the equipment in row 1 and the date in column A as such:

[TABLE="width: 250"]
<tbody>[TR]
[TD][/TD]
[TD]D1[/TD]
[TD]D2[/TD]
[TD]D3[/TD]
[/TR]
[TR]
[TD]01/04[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]02/04[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]

I am trying to create a user form to enter the data as the sheet is quite large. The userform looks like this,

date (text box)
Select vehicle (combobox)
Enter fuel amount (text)
Enter data (command button)

I am failing to find any code to use in the command button as i have only very basic knowledge of VBA so that when it's clicked, it uses the date and the vehicle selection to put the fuel amount into the right cell. Any assistancewould be greatly appreciated