How do I create or understand text boxes??

I would agree with your assessment.  The encoding is likely more related to the backend processing that is tied to the form, rather than the server itself.

"The input size attribute specifies the visible width, in characters, of an input field.

The default value for size is 20.

Note: The size attribute works with the following input types: text, search, tel, url, email, and password."

For this when you are looking at the size property, 20 states that 20 characters will be visible in the input field. If the maxlength is 40, then only 20 characters would be visible at any given time. The second part of Nancy's response has to do with input field types. Text and password are types that have been around much longer and show either plain text or asterisks in place of text when typed. The other fields like tel and email are newer and related to the HTML5 spec. Those also show different keyboards to mobile users to make it more accessible and easier to edit then using a traditional keyboard. For instance, tel, for a phone number doesn't show the alphabet keys.  

As far as maxlength, I would consult with your client because this appears to be connected to something on the backend and if they have limits, your form could result in unintended errors if you are not matching the data they are expecting.

WIth regards to the cols you are showing, this is a textarea field type which is different from the input type discussed in the beginning of this post. Textareas have dimensions to them in terms of rows and columns.  This says how wide and tall the area should be. Typically in this area you would expect paragraphs to be typed for a response, much longer than a single line of text.  In this field type, cols is similar to the size in that it tells how wide the textarea will be on the screen. Rows will tell how tall the textarea object is.