I am afraid there is some confusion in your mind:
- a header is some data repeated unchanged at top of pages
- a heading is the “title” of some part of the document, like a chapter title, sub-chapter title, …; it lies within the main text area
In your sample, the (empty) header is correctly styled Header. Note that default configuration applies a proper style to header and footer (Footer) so that these data can be formatted separately from your main topic (Body Text).
In case, you want to change the style of any paragraph, put the cursor inside this paragraph and apply another paragraph style (double-click on the name in the style side pane). It works if there is no direct formatting. When direct formatting is present, it takes precedence over styles; therefore, you must first clear direct formatting to see the effect of styles.
Writer is not an image processing program. It has very limited possibilities (just the bare minimum). Consequently, the put all odds on your side, I recommend you prepare your images/logos outside Writer so that Writer uses them “as is”, without any transformation. In other words, crop, resize, rotate your images; adjust dpi, colours and all other parameters before pasting or inserting into Writer. Then the image is simply a rectangle to be managed as a simple object.
After insertion, the image is a frame upon which frame style Graphics is applied. Frame styles have a tab Type where you configure anchor and position properties.
Anchor is the reference point in your text to which the frame is attached. The anchor determines the page where the frame appears. If the anchor is moved because of edits in your discourse and reaches another page, the frame will follow and be displayed in this page. The frame is always painted in the same page as the anchor.
Position sends the frame where you want it. It can be specified as absolute coordinates anywhere in the page, or “context” relative coordinates (in margins or paragraph bounding box; left, centre, right and top, centre, bottom).
Another important tab is Wrap which tells how the frame interacts (or not) with text (I highly recommend you untick Allow overlap which is now enabled by default and this is faulty IMHO).
Your sample shows you have 2 logos in the footer, one at left, the other one at right. This means you need two frame styles so that you can position differently the logos (one at left of paragraph area, the other at right of paragraph area).
Frames are extremely (this word should be repeated seven times!) sensitive to direct formatting (DF), infinitely more than paragraphs or characters. The least suspicion of a shadow of DF is enough to mess up style application and this kind of DF is so pernicious that it is next to impossible to get rid of it once it is set.
This is why beginners (and even experienced users) often prefer to choose As character anchor which turns the image into a (huge) glyph which is then managed by the standard text flow algorithm. You no longer sweat upon position parameters and don’t fear DF. This is the easiest and most reliable way when your images “integrate” smoothly with your text.
This is probably the solution of choice in your case: first logo As character, a Tab, page number and page count fields, a Tab, LO logo. I have “moved” page number/count in the middle to avoid complex handling of data at right of page (which would necessitate a frame style).
EDIT:
I didn’t mention anchor To page. This is a special mode which attaches the frame to a designated physical page, no matter how you edit your text (edits may create undeletable blank pages between end of text and frames). The frame is irremediably attached to this page for ever.
It is a feature providing a poor substitute for DTP (desktop publishing) applications for people not wanting to switch. Unless you know the full consequences of this mode, don’t use it. It will cause more problems than it solves. Remember that a frame can be sent anywhere in the page through Position parameters and this is what most users want.