I am working with member API and i am trying to upload the image when registering. After i register the member and open backoffice i see this:

Controller

public class RegisterController : SurfaceController
{
    // GET: Register
    public ActionResult Register(Models.RegisterModel model)
    {
        if (!ModelState.IsValid)
            return CurrentUmbracoPage();

        var memberService = Services.MemberService;

        if (memberService.GetByEmail(model.Email) != null)
        {
            ModelState.AddModelError("", "A member with that email alredy exists");
            return CurrentUmbracoPage();
        }

        var member = memberService.CreateMemberWithIdentity(model.Email, model.Email, model.Name, "bMEMembers");

        member.SetValue("companyName", model.CompanyName );
        member.SetValue("avatar", model.Avatar);


        memberService.SavePassword(member, model.Password);
        Members.Login(model.Email, model.Password);

        memberService.Save(member);

        return Redirect("/");
    }
}

Model

public class RegisterModel
{
    [Required]
    public string Name { get; set; }

    [Required]
    [EmailAddress]
    public string Email { get; set; }

    [Required]
    public string Password { get; set; }

    public string CompanyName { get; set; }

    public HttpPostedFileBase Avatar { get; set; }

    public string ExistingProfilePicture { get; set; }
}

View

 <fieldset>
    @Html.LabelFor(model => model.Name)

    @Html.EditorFor(model => model.Name)

    @Html.ValidationMessageFor(model => model.Name)


    @Html.LabelFor(model => model.Email)

    @Html.EditorFor(model => model.Email)

    @Html.ValidationMessageFor(model => model.Email)


    @Html.LabelFor(model => model.Password)

    @Html.PasswordFor(model => model.Password)

    @Html.ValidationMessageFor(model => model.Password)


    @Html.LabelFor(model => model.CompanyName)
    @Html.EditorFor(model => model.CompanyName)
    @Html.ValidationMessageFor(model => model.CompanyName)

    @Html.LabelFor(model => model.Avatar)
    <input type="file" name="Avatar" />
    @Html.ValidationMessageFor(model => model.Avatar)

    <input class="btn" type="submit" value="Create" />
</fieldset>

I am using Umbraco 8 and i followed tutorial from Umbraco TV