Best way to teach yourself VBA is to simply get stuck in, plenty of online resources to learn VBA and to be honest the amout of VBA you use when connecting to gruss is usually very basic stuff so a course on VBA would most likely be overkill.
Which bits of Gruss are you strugging with? Plenty of code examples on the forum and helpful posters, alternatively people like Osknows take on projects and is well regarded on the forum
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