It is really hard to show you how to long division in this math editor, but I will try to help.
First of all, approximately you are asked to divide 100/3000; therefore your answer is going to be approximately .03.
Then write the divisor down the a vertical line and then to the right of the vertical line write the dividend followed by a decimal point and at least 2 zeros like this:
3498 | 97.00
Now draw an horizontal line across the top of the 97.00 and touching the vertical line.
Above the horizontal line put a decimal point above the decimal point in the dividend.
Now since 3498 will not divide into 970 put a zero next to the decimal point in the quotient.
Then 3498 goes into 9700 twice, put the 2 in the quotient and write the product of 2 and 3498 underneath the 9700 and subtract. This should begin to look familiar now...so carry on.