Assist pls-how to merge 2 images

[Low_tech_gimper]

Hi, I'm a gimp novice & would appreciate some help.  I have 2 photos: a nice portrait with a poor background & a photo with a lovely lighthouse & bay at dusk.  Using intelliigent sissors I've clipped the person's portrait in first photo & have it as a layer w/checkerboard background.   I have the background photo as a layer & then position the portrait into the photo w/lighthouse background.    The background photo has the flashing dotted lines of the portrait silhouette but image isn't completely visible only the very bottom of the portrait which I moved to get the lighthouse into view, even when I "chain" them together.  The portrait & the background are  where I want them but cant seem to get the entire portrait to become visible.   Could someone please suggest a solution as this is my first time gimping or perhaps order of ops from the beginning. Please be overly explicit in explaining.  Thank you!!

[rich2005]

Not 100% sure about your workflow but it reads like you have your background layer (the lighthouse) as the image size, the canvas and have the portrait (with transparency) on top of that.

You can move that top layer around and move it off the canvas and parts vanish. To see all use View -> Show All

To increase the canvas size to hold all the layers use Image -> Fit Canvas to Layers and if you want, turn off Show all.

You will be left with an image with blank areas where the new image size is larger than the original layer sizes.

30 second example: https://i.imgur.com/FHY2mfr.mp4

Up to you what to do now, maybe use the crop tool or put a new coloured layer at the bottom ...

[Low_tech_gimper]

Thank you for the reply. I tried the show all toggle & unfortunately the portrait didn't become visible. I opened the portrait as an alpha channel & removed the background.  Also I think the background (lighthouse) was opened as an alpha channel.   How do I designate the background as canvas? Is there a toggle?  Should I go to background layer & then turn off alpha channel? Sorry I'm lost. Thank you again.

[sallyanne]

You need to have your background selected, it is usually the 'image, if you opened it first' so that will be what is changed in size with canvas.
If you do not want to add extra on the outside of your scene you could scale the background up a little. You would need to select just the background layer to scale, use image > scale.
If that still doesn't work you could also scale your portrait layer down so it fits on your background. This time layer > scale.

[Low_tech_gimper]

Thank you. It worked! The images are configured as I want them, but there's some artifact around the person's hair (some brightness in her hair & a bit of the checkboard) that needs to be corrected. What tool & steps would you suggest to correct? Finally, could you please tell me how to save this & what format (png?)? I ultimately want to send this image to Costco for a New Year's card.  Thank you again for your patience & assistance.

[sallyanne]

As for the artifact around her hair you need to show a snippet of your picture or the whole. Where is the checkboard? Usually means there is some transparency.
As for a file, if you want to keep transparency png or most printers prefer jpg but if you have transparency in your picture it will show up as the background colour in your gimp when you save it